The present invention relates to a ski boot comprising a variable-volume shell which is at least partially made of molded plastic and is divided, by a longitudinal opening line, into an outer side and an inner side, one of these sides having a flap that has a front lateral side and a back lateral side, this flap being applied onto the other side when the boot is being closed.
Modem variable-volume ski boots comprise a shell which closes over the foot by two flaps that are applied onto one another by closing and tightening means. The front ends of these flaps define a transverse slot in the forward part of the shell to allow the flaps to be opened, so as to make it easier to insert the foot into the boot. To make the shell waterproof at the location of this slot, a seal is generally arranged on an area of the shell extending under the ends of the flaps. This seal also generally has a continuation extending beyond the ends of the transverse slot, to ensure proper waterproofing at the ends of the slot. However, even in the compressed state, it is found that such a seal does not fully prevent the water from entering at the particularly exposed front end of the flaps. This is due to the surface discontinuity appearing at the lateral edge of the low flap covered by the high flap. This discontinuity creates a space which is never completely occupied by the rubber of the seal since the latter, even when pliable, cannot deform enough to completely block entry to this space.
The use of a synthetic foam that has open cells and is therefore highly compressible does not make it possible to improve the waterproofing, because it is found that moisture penetrates the foam by a pumping effect, then subsequently penetrates inside the shell. Utility model DE 83 36 239 has proposed to use a piece of elastic material having ribs next to the flaps, the elastic compression of these ribs by the flaps being supposed to provide better waterproofing. This improvement does not, however, make it possible to solve the problem mentioned above.
Patent EP 0 583 565 describes a sealing piece having two wings, one of these wings extending under the low flap and to the front of it, while the other wing extends between the two flaps. The waterproofing is indeed improved toward the front, but a discontinuity is formed at the rear, below the instep. Further, at the front, the raising of the high flap creates snow retention that compromises the waterproofing. This thickening of the high flap also causes lateral discomfort.
The design described in utility model DE 297 19 568 has proposed to improve the waterproofing by eliminating the transverse slot on one of the sides of the longitudinal opening line, so that there is essentially only a single flap. The remaining transverse slot is closed by a seal having a variable profile. The problems inherent in the presence of a compressible seal remain. Document EP 0 683 991 proposes a design without a seal. As in the case mentioned above, the variable-volume shell is provided with a single flap whose front end is continued by a tab that covers almost all of the forward part of the opening line. In this case, the waterproofing is provided by applying this tab onto the shell. It is obvious that this type of closure is not completely waterproof. An uncovered transverse slot is also left. The waterproofing can be improved by covering this tab with an extension of a closing strap.
U.S. Pat. No. 6,021,589, in the name of the Applicant, moreover discloses a ski boot comprising a flexible upper in the form of a sock, enclosed by a frame in the form of an open hoop fixed to the flexible upper by a plastic injected around the frame and through the open sole.
The present invention draws on this last design to provide waterproofing at the flap without an auxiliary seal.
The boot according to the invention is more precisely distinguished by the fact that the top of the boot, in which the flap is formed and in which the longitudinal opening line is located, forms part of a flexible upper that is enclosed, in its low part, by the molded plastic part, and in that the front lateral side of the flap is connected to the upper by an extensible elastic part.
The extensible elastic part is preferably made of elastic, more precisely bi-elastic, fabric.
According to a preferred embodiment of the invention, the high part of the flexible upper, intended to enclose the ankle, is also connected to the flap and to the part on the opposite side from the flap by extensible elastic parts.